Automatic door operators for residential garage doors are known in the art. The typical prior art system includes a portable radio frequency transmitter which can be disposed in the user's automobile. It is also typical to include a permanently mounted momentary contact pushbutton switch within the garage for control of the garage door.
The typical pattern of use is as follows. The user enters the garage and opens the closed garage door by momentary depression of the pushbutton switch. The automatic door operator moves the garage door from the fully closed position to the fully opened position. The automatic door operator includes some mechanism for detection of when the door has reached this fully opened position to stop the door. The user enters his automobile, starts it and then leaves the garage. After clearing the garage door, the user presses a momentary contact pushbutton on the portable radio frequency transmitter. This transmits an encoded signal to the automatic door operator. The automatic door operator determines whether or not the received radio frequency signal is correctly encoded for that particular automatic door operator. If this is the case, then the automatic door operator closes the door and stops when the fully closed position is detected. When the user returns, the process is reversed. The user presses the pushbutton switch on the portable radio frequency transmitter, the automatic garage door operator opens the door allowing the user to park his automobile within the garage. Then the user exits the automobile and closes the garage door by momentary actuation of the garage mounted pushbutton. The typical automatic door operator also enables the operator to stop movement of the door when it is partially opened or partially closed by additional activation of either the pushbutton switch or the portable radio frequency transmitter.
All such automatic door operators are required to solve two types of problems during their control operation. Firstly, the automatic door operator needs some manner of detecting when the door has reached the fully opened or the fully closed position. Secondly, the automatic door operator needs some manner of determining when the door has encountered an obstructing object during its operation. In older automatic door operators these functions were carried out employing mechanical switches. An open switch and a close switch coupled in some manner to the drive train of the automatic door operator were tripped when the door reached their respective positions An obstruction was detected when a tension sensitive mechanical switch connected to the drive train of the automatic door operator detected greater than a predetermined amount of force applied to the door.
In recent years there has been interest in control of the obstruction and limit functions electronically. This interest is driven by the great reduction in the expense of electronic controllers, coupled with their greater versatility as compared to mechanical controllers. The typical electronic controller of the prior art includes some manner of detection of shaft rotation of the motor which drives the door. This typically takes places by detection of pulses produced by motor shaft rotation. The rate of generation of these rotation pulses is a measure of the speed of door travel. In a typical installation the torque developed by the motor driving the door is inversely proportional to the motor speed. Electronic obstruction detection has heretofore detected whether or not the motor speed is less than a predetermined speed corresponding to the greatest permitted torque. This greatest permitted torque is set greater than the torque required for ordinary operation of the door but less than a damaging torque. Open and close limit detection takes place by comparison of a count of these shaft rotation pulses with numbers corresponding to the respective limit positions.
There remains some problems in implementing the electronic limit detection and electronic obstruction detection in accordance with the prior art. It is not heretofore known how to easily select a particular torque limit value for a particular installation. It is also heretofore not known how to easily adjust the open and closed limit numbers for a particular garage door installation. Automatic door operators such as typically employed for residential garage doors are manufactured in large numbers and typically a single electronic controller must be capable of installation in a variety of settings. Thus, it would be useful in the art to provide a convenient means for setting the torque obstruction limits and setting the travel limits in such automatic door operators.